1. Field of the Invention
The present invention relates to a recording medium such as BD-ROM (Blu-ray Disc ROM) which has a capability to restrict unauthorized duplication of data written therein, which includes physical mark information and an apparatus and methods for forming, recording, reproducing, and restricting reproduction of illegally duplicated recording media.
2. Description of the Related Art
Recently, standardization of new high-density rewritable optical discs has rapidly progressed, for example, BD-RE (Blu-Ray Disc Rewritable), which can store a large quantity of high-quality video and audio data. As a result, products associated with such discs have also been developed. Such products are expected to be commercially available in the near future.
Referring to FIG. 1, the disc structure of a conventional BD-RE is shown. As shown in FIG. 1, the BD-RE has a center hole and a clamping area which are adapted to allow the optical disc to be loaded in position in an optical disc apparatus. The optical disc also has an information area for recording disc management information and data thereon.
A lead-in area (LI), a data area, and a lead-out area (LO) are assigned to the information area. A burst cutting area (BCA) is assigned to the area preceding the lead-in area. The BCA, which is not a writable area, contains information modulated into a format unique to BD-RE.
Referring to FIG. 2, an example of an optical disc apparatus applicable to BD-RE is shown. As shown in FIG. 2, the optical disc apparatus includes an optical pickup 10, a video disc recorder (VDR) system 11, and an encoder 12. The optical disc apparatus performs a data recording operation for encoding and modulating data, externally input thereto, into a format unique to BD-RE, and then recording the modulated data on a data area assigned to the information area of the BD-RE. The optical disc apparatus also performs a data reproduction operation for reading out data recorded on the data area, and processing the read-out data to reproduce original video and audio data.
The optical disc apparatus having the above-mentioned configuration can record audio/video (A/V) data of a movie or broadcasted program on a BD-RE optical disc 100, and subsequently reproduce the recorded A/V data from the BD-RE optical disc 100 in the form of high-quality video and audio.
The development and standardization of high-density read-only optical discs, such as BD-RE and its read-only counterpart, BD-ROM (Blu-ray Disc Read-Only Memory), and write-once Blu-ray discs such as BD-R (Blu-ray Disc Recordable) have recently been progressing. However, there is no effective solution for preventing unauthorized duplication of data streams, written on a BD-ROM, or onto other optical discs, such as BD-RE or BD-R.